Height & Weight Percentile Calculator

A height percentile places a child's standing height within a same-age, same-sex reference distribution. A result near the 75th percentile means roughly 75% of that reference group has a lower height and 25% a higher height. It does not mean the child is 75% of adult height.

The 50th percentile is the median: the midpoint of the distribution. It is not an ideal that every child should reach. Healthy children can naturally be shorter or taller than this point, and family stature contributes to those differences.

Enter age at measurement, even if you are checking an older record. Use completed years and additional months: for 8 years and 9 months, enter 8 and 9 rather than rounding up to 9 years.

Select the CDC reference sex and your units, then enter standing height, weight, or both. Each measurement has its own result. Changing an input clears the old result; calculate again to update the chart.

• Supported interval: 24 through 240 months, including exactly 20 years.
• Metric or imperial input; results and chart reference values use cm and kg.
• Use the chart tabs to compare height-for-age and weight-for-age separately.
• Add up to 12 measurements during this visit, entering the age for each one. Dates are optional labels. Download a CSV before leaving to keep these percentile records. Separate optional browser history can save dated height measurements for the growth velocity tool; it does not save the full percentile record.

Measure standing height without shoes on a firm, level surface, preferably with a stadiometer. Keep legs straight, shoulders relaxed and the head level, looking ahead. Lower the headpiece gently onto the top of the head. A tape fixed to a wall and a rigid right-angle book can help at home, but may introduce more error.

Weigh on a stable digital scale with shoes and heavy outer clothing removed. Repeat an unexpected reading before entering it. Time of day, clothing, posture and equipment can change the number enough to move a percentile, especially for a small child.

• Measure twice and resolve a large difference with another reading.
• Record the date, units and equipment used.
• Use standing height here; infant recumbent length is a different measurement.
• Do not interpret small day-to-day movements as a growth trend.

Height-for-age compares stature with age peers. Weight-for-age compares body mass with age peers, without considering how tall they are. A tall child may have a high weight percentile partly because a larger body weighs more. Two children with the same weight percentile can have very different heights and body compositions.

The gap between these two percentile numbers is not itself a diagnostic measure. This calculator does not label a child underweight, overweight or obese. Clinicians may use BMI-for-age, history, examination and other information when evaluating weight in children and adolescents.

The calculation uses the CDC 2000 stature-for-age and weight-for-age data files for ages 2–20. The files provide sex-specific L, M and S parameters at defined ages. M is the median; S describes variation; L is a Box–Cox power that accounts for the distribution's asymmetry.

Between reference ages, the tool linearly interpolates L, M and S, calculates a z score, then converts it to a percentile using the standard normal distribution. When L is zero, it uses the logarithmic form below.

At exactly 24 months, the CDC boys' stature-for-age median is 86.45220101 cm. Entering that height at 2 years and 0 months produces a height percentile of 50. The matching weight-for-age median is 12.6707633 kg; entering that weight also produces a weight percentile of 50.

These precise values are useful for checking the mathematics, not for measuring a child to eight decimal places. In practice, input precision should match your equipment. The calculator rounds the displayed result and shows very extreme percentiles as below 0.1% or above 99.9%, avoiding a misleading impression of certainty.

A single measurement describes a moment. Several well-measured points reveal whether growth broadly follows a consistent path, speeds up or slows down. Pubertal timing can shift a child's position relative to peers because children do not all have their growth spurt at the same age.

A changing percentile is not automatically a problem. Measurement errors, different equipment and normal developmental variation can contribute. Persistent changes, slowed height growth, unexplained weight change or other symptoms deserve a discussion with the child's clinician, who can examine the full record rather than one web result.

CDC 2000 charts describe a US reference population assembled from historical survey data. They are not a real-time average of every child worldwide. A country-specific growth standard, a WHO chart or a specialist chart may be more appropriate in a particular clinical setting. Results from different references can differ even when the measurements are identical.

This tool is limited to standing height and weight from age 2 through age 20. It does not use infant length charts, gestational-age corrections, condition-specific charts or individualized puberty assessments. It does not predict final adult height. Very extreme values need additional care because ordinary LMS extrapolation is less reliable far beyond the main reference distribution.

P50 is not a goal, and a higher percentile is not a better score. Interpretation depends on family height, previous measurements, development and medical history. A child at a low or high percentile can be healthy; a result near the middle cannot confirm health on its own.

Do not change a child's diet, supplements or medication to chase a chart line. If a reading seems surprising, first verify the age, units and technique, then seek professional advice if concerns persist. The calculator is an educational way to understand reference data, not a substitute for individualized care.

The growth chart shows position within a reference group. The free 3D height comparison shows how measured heights look together: place a child alongside a parent or sibling to make the difference easier to picture.

Enter current measured heights and label each person clearly. The 3D view illustrates scale; it does not add a health assessment or predict future growth.